Pipe in concrete slab, rather than rebar?

[Jstpssng]

We have some old 1 1/2" heat pipe which is somewhat pitted, so not suitable for anything else which I would use it for such as a flagpole. I've been thinking about using it for reinforcement, and am wondering if losing that much concrete would affect the structure. It will just be in a couple of small outbuildings, so not that much harm done if it doesn't work as planned; and definitely better than a gravel floor.

 

[Hay Dude]

If the concrete is only 4” thick and the pipe is 1.5” diameter, that’s not much concrete above and below. Rebar only 1/2”-5/8“ so lots more concrete above and below. If I had to guess, the concrete will crack where the pipe is.
Thicker concrete would help, but more costly.

 

[Jstpssng]

If the concrete is only 4” thick and the pipe is 1.5” diameter, that’s not much concrete above and below. Rebar only 1/2”-5/8“ so lots more concrete above and below. If I had to guess, the concrete will crack where the pipe is.
Thicker concrete would help, but more costly.

You express the same concerns which I have. 4 inches is too thin here anyways, most slabs are 6 or better. That still only leaves 3 1/2 inches of concrete unless I poured thicker as you say. At current prices of 125$/yard for concrete, it's probably cheaper to buy rebar.

 

[fruitcakesa]

You express the same concerns which I have. 4 inches is too thin here anyways, most slabs are 6 or better. That still only leaves 3 1/2 inches of concrete unless I poured thicker as you say. At current prices of 125$/yard for concrete, it's probably cheaper to buy rebar.

Looks like 1/2" rebar is averaging $2/ft retail and only about $.70/ft for 5/8" from steel suppliers

 

[Jchonline]

If you are spending the money on concrete then just get the rebar.

 

[EddieWalker]

If you are spending the money on concrete then just get the rebar.

I agree, just get the rebar.

 

[JM7500]

I would be concerned with the surface of the pipe. Rebar is not smooth like a pipe wall. The pipe may “slip” in the concrete. The ridges in the rebar helps with tension with in the slab.

 

[Cat_Driver]

ALWAYS use fibers in your cement. I laid a 4" pad of cement with fibers on beach sand with no gravel base. That was 25 years ago and zero cracks. I did the same without fibers but with a gravel base, rebar, and it's got plenty of cracks. Either stainless steel or fiberglass.

 

[dodge man]

Rebar is “deformed” which all those little ridges grab the concrete. Pipe woukd be to smooth and to big, my guess it would weaken the slab not make it stronger.

 

[fried1765]

We have some old 1 1/2" heat pipe which is somewhat pitted, so not suitable for anything else which I would use it for such as a flagpole. I've been thinking about using it for reinforcement, and am wondering if losing that much concrete would affect the structure. It will just be in a couple of small outbuildings, so not that much harm done if it doesn't work as planned; and definitely better than a gravel floor.

Find another use for the pipe!